tbuckley/cabot-search huggingface dataset:
Abstract P3034: Acute Reduction Of Cardiac Sodium Channel Nav1.5 Increases Mitochondrial Calcium And Rewires Cardiac Metabolism
Authors: xiaoming zhang, Jared McLendon, Ethan J Anderson, Barry London, Ryan L Boudreau
Journal: Circulation Research (2022)

SCN5A encodes the voltage-gated Na + channel Na v 1.5, known for its role in cardiac conduction. However, we recently found unexpected links between lower SCN5A expression and increased non-arrhythmic death in heart failure (HF) patients. To test if lower SCN5A expression in mice causes worse HF, we subjected young heterozygous SCN5A null ( SCN5A +/- ) mice to transverse aortic constriction (TAC), a model of cardiac hypertrophy progressing to HF. Surprisingly, SCN5A +/- hearts resisted TAC-induced hypertrophy and showed gene expression changes consistent with metabolic inflexibility [i.e. maintained fatty acid oxidation (FAO), blunted shift to glycolysis]. Given published roles for Na + in mitochondrial redox biology and metabolism, we assessed related phenotypes in SCN5A +/- mice. We found that aged SCN5A +/- mouse hearts show increased reactive oxygen species (ROS) and transcriptomic changes indicative of elevated FAO and lower glycolysis. Metabolomics data revealed perturbed glycolytic flux in SCN5A +/- mouse hearts, and cardiomyofiber respiration assays showed that these hearts maintain elevated FAO after insulin. We assessed if acute reduction of Na v 1.5 in mouse hearts (by AAV:Cre in SCN5A -flox mice) elicits metabolic changes. Both SCN5A +/fl and SCN5A fl/fl mouse hearts at 3 weeks post-AAV:Cre injection (vs. AAV:GFP) showed robust dampening of mitochondrial gene expression and altered metabolite profiles, including decreases in several fatty acids. We explored the possibility that these observations may relate to mitochondrial Na + /Ca 2+ imbalance. We found that acute reduction of myocardial Na v 1.5 expression in mice leads to reduced mitochondrial Na + /Ca 2+ exchanger (Nclx) protein levels, supporting potential crosstalk between these proteins, which is consistent with recent data suggesting that inward Na + via Na v 1.5 primes Nclx to promote Ca 2+ efflux from nearby mitochondria. Indeed, we found that acute silencing of Na v 1.5 expression leads to increased mitochondrial Ca 2+ in cardiomyocytes. Overall, these data further highlight an important Na v 1.5 interface with mitochondrial biology and support the notion that reduced Na v 1.5 levels triggers ROS accumulation and metabolic imbalances in heart, which may exacerbate HF in patients.
Abstract P1066: Monoamine Oxidase A And Organic Cation Transporter 3 Coordinate Intracellular Adrenergic Signaling To Calibrate Cardiac Function
Authors: Ying Wang, Meimi Zhao, Bing Xu, Yang K Xiang
Journal: Circulation Research (2022)

Aims: We have recently identified a functional pool of intracellular β 1 adrenergic receptors (β 1 ARs) crucial for cardiac function. However, the systematic signaling network of intracellular β 1 ARs remains elusive. Here, we aim to uncover the integrative control of cardiac function, compartmentalized β 1 AR signaling, and potential interface between two critical modulators of catecholamine homeostasis, MAO-A and OCT3. Methods and Results: Cardiac deletion of MAO-A (MAO-A-CKO) elevated myocardium catecholamines, cAMP levels and cardiac ejection fraction by disrupting intracellular catecholamine degradation. Deletion and pharmacological inhibition of MAO-A both enhanced cardiac adrenergic response, with elevated ejection fraction and heart rate. Inhibiting OCT3 by corticosterone prevented the impacts of MAO-A inhibition on cardiac function. Using subcellular anchored Förster resonance energy transfer (FRET) biosensors, we then determined the regulation of compartmentalized β 1 AR/PKA signaling at the sarcoplasmic reticulum (SR) and plasma membrane (PM) microdomains. We also examined local PKA-substrates phosphorylation and myocyte excitation-contraction coupling. MAO-A deletion and inhibitor (MAOi) enhanced local PKA activity at the SR, phosphorylation of phospholamban, Ca 2+ cycling, and contractile response. Whereas overexpression of MAO-A impairs SR-localized PKA activity and phospholamban phosphorylation. In contrast, these modifying of MAO-A did not affect PKA activity at PM and L-type Ca 2+ channel phosphorylation. Inhibiting OCT3 blocked blocking catecholamine transport and diminished the efficacy of MAO-A inhibitor (MAO-A) and MAO-A-CKO to regulate SR-localized β 1 AR signaling. In parallel, OCT3 inhibition and deletion prevented the MAO-A-dependent enhancement of Ca 2+ cycling and cardiac contractile function. Conclusion: Together, we show that MAO-A and OCT3 act in a concert to fine-tune the intracellular catecholamines, activation of SR-localized β 1 AR-PKA signaling, and cardiac fight-or-flight response. Further, we reveal a drug contraindication between anti-inflammatory corticosterone and anti-depressant MAOi in modulating adrenergic regulation in the heart, providing novel perspectives of those drugs in cardiac implications.
Abstract P1014: Cardiomyocyte Energetic Capacity Governs Responses To Cell Cycle Stimulation
Authors: Abou bakr M Salama, Qinghui Ou, Riham Abouleisa, Tamer Mohamed, Bradford G Hill, Ahmad Gebreil, Collin Wells
Journal: Circulation Research (2022)

Background: Induction of cardiomyocyte (CM) proliferation is a promising strategy for cardiac regeneration. We previously showed that the overexpression of four cell cycle factors (4F), i.e. cyclin B1, CDK1, cyclin D1 and CDK4, induces CM proliferation. Temporal profiling of the single cell transcriptomes of 4F- and LacZ-overexpressing CMs showed a specific population with higher levels of CD36 that was more responsive to the 4F cell cycle induction. In addition, P7 primary CMs isolated from CD36 KO mice demonstrated 50% less response to the 4F compared with the WT controls (Abouleisa et al., Circulation, 2022). These data indicate that CD36 may be required to prime CMs to proliferate. CD36 is known to internalize fatty acids to be utilized for energy production. Here, we aim to investigate the direct effect of CM energetic capacity on their response to cell cycle stimulation. Methods and Results: Carnitine palmitoyl transferase -1 (CPT-1) is a rate limiting enzyme for the β-oxidation of fatty acids. Knockdown of CPT-1 using siRNA significantly reduced mitochondrial ATP production by 10% and led to a significant reduction in cell cycle markers (PHH3, EDU) in response to the 4F (PHH3; control siRNA+4F:24±1% vs CPT1 siRNA+4F:15±1%, EDU; control siRNA+4F:22±2% vs CPT1siRNA+4F:16±1%, P&lt;0.01, n=4). Small molecule inhibition of CPT1 using etomoxir significantly decreased mitochondrial ATP production and suppressed CM responses to the 4F. Furthermore, overexpression of CPT-1 using viral vectors resulted in significant increase in ATP production and increased response to cell cycle stimulation using the 4F. Supplementing the culture medium with (1μmol) L-carnitine significantly increased mitochondrial ATP production and enhanced the CM response to the 4F. Finally, to increase ATP availability in CMs directly, we overexpressed a light-activated mitochondrial proton pump (MT-ON). CMs expressing MT-ON showed a significant increase in mitochondrial ATP levels and enhanced cell cycle induction in CMs transduced with 4F (PHH3; 4F:18±2% vs 4F+MT-ON:27±3%, EDU; 4F:18±1% vs 4F+MT-ON:30±4 %, P&lt;0.01, n=4). Conclusions: These findings suggest that an energy threshold is required for CMs to progress into the cell cycle.
Abstract P3011: Nrf2 Transcriptional Upregulation Of Idh2 To Tune Mitochondrial Dynamics And Rescue Angiogenic Function Of Diabetic Epcs
Authors: Xiaozhen Dai, Kai Wang, Qian Lin, Chen Oscar, Danile J Conklin, Kupper A Wintergerst, Lu Cai, Zhongbin Deng, Yi Tan
Journal: Circulation Research (2022)

Endothelial progenitor cells (EPCs) are reduced in number and impaired in function in diabetic patients. Whether and how Nrf2 regulates the function of diabetic EPCs remains unclear. In this study, we found that the expression of Nrf2 and its downstream genes were decreased in EPCs from both diabetic patients and db/db mice. Survival ability and angiogenic function of EPCs from diabetic patients and db/db mice also were impaired. Gain- and loss-of-function studies, respectively, showed that knockdown of Nrf2 increased apoptosis and impaired tube formation in EPCs from healthy donors and wild-type mice, while Nrf2 overexpression decreased apoptosis and rescued tube formation in EPCs from diabetic patients and db/db mice. Additionally, proangiogenic function of Nrf2-manipulated mouse EPCs was validated in db/db mice with hind limb ischemia. Mechanistic studies demonstrated that diabetes induced mitochondrial fragmentation and dysfunction of EPCs by dysregulating the abundance of proteins controlling mitochondrial dynamics; upregulating Nrf2 expression attenuated diabetes-induced mitochondrial fragmentation and dysfunction and rectified the abundance of proteins controlling mitochondrial dynamics. Further RNA-sequencing analysis demonstrated that Nrf2 specifically upregulated the transcription of isocitrate dehydrogenase 2 (IDH2), a key enzyme regulating tricarboxylic acid cycle and mitochondrial function. Overexpression of IDH2 rectified Nrf2 knockdown- or diabetes-induced mitochondrial fragmentation and EPC dysfunction. In a therapeutic approach, supplementation of an Nrf2 activator sulforaphane enhanced angiogenesis and blood perfusion recovery in db/db mice with hind limb ischemia. Collectively, these findings indicate that Nrf2 is a potential therapeutic target for improving diabetic EPC function. Thus, elevating Nrf2 expression enhances EPC resistance to diabetes-induced oxidative damage and improves therapeutic efficacy of EPCs in treating diabetic limb ischemia likely via transcriptional upregulation of IDH2 expression and improving mitochondrial function of diabetic EPCs.
Abstract P2055: Secondary Structure And Antisense Oligonucleotides Regulate Cardiac Messenger RNA Translation And Modulates Cardiomyocyte Hypertrophy
Authors: Peng Yao, Omar Hedaya, KADIAM VENKATA, feng jiang, Jiangbin Wu, EngSoon Khor
Journal: Circulation Research (2022)

Translation of upstream open reading frames (uORFs) typically abrogates translation for the main ORF (mORF) and regulates protein expression. uORFs are present in nearly 50% of messenger RNA (mRNA) transcripts, but their impact and regulation on biological processes are understudied. Mining of ribosome profiling data from next-generation sequencing analysis of human and mouse hearts reveals that most translated uORFs reside within mRNAs of transcription factors, which play essential roles in cardiomyocyte (CM) development and growth. We show that the uORF start codon synergizes with an immediate downstream double-stranded RNA (dsRNA) element to activate uORF and inhibit mORF translation. Biochemical and genetic evidence support that this mechanism is utilized by mRNAs encoding multiple transcription factors such as GATA4 (GATA binding protein 4), encoding a master transcription regulator of CM differentiation and pathological hypertrophy. Intriguingly, a trans-acting regulatory factor, DEAD-box RNA helicase DDX3X, is involved in unwinding the dsRNA structure and promoting mORF translation. We develop two types of antisense oligonucleotides (ASOs) that mimic the unwinding or stabilizing of the dsRNA secondary structure, thereby suppressing or enhancing the translation of this uORF, respectively. Genetic or chemical inactivation of this GATA4 uORF using CRISPR-Cas9 or ASOs in human embryonic stem cells lead to enhanced differentiation into CMs and cellular hypertrophy. At the organismal level, short-term treatment of isoproterenol and surgery-induced cardiac hypertrophy mouse models with uORF-enhancing ASOs reduces GATA4 mRNA translation and antagonizes cardiac hypertrophy and remodeling. As a summary, this uORF-dsRNA element is a new tunable regulator of cardiac transcription factor mRNA translation and can be targeted to alter cellular and organismal phenotypes. Moreover, mechanism-based translation-manipulating ASOs can serve as promising biotechnological tools to regulate gene expression in vitro and in vivo and can be adapted to create novel RNA-based therapeutics.
Abstract P1099: Evidence Of Sialylation Pathway Alterations In Peripheral Blood Of Brugada Syndrome Patients
Authors: Andrea Ghiroldi, Giuseppe Ciconte, Pasquale Creo, Adriana Tarantino, Sara D'Imperio, Marco Piccoli, Federica Cirillo, Emanuele Micaglio, Monasky Michelle, Emanuela Locati, Gabriele Vicedomini, Carlo Pappone, Luigi Anastasia
Journal: Circulation Research (2022)

Brugada syndrome (BrS) is a cardiac arrhythmia associated with a higher risk of SCD. BrS is considered a genetic disorder, and the most commonly mutated gene is SCN5A, encoding the alpha subunit of the voltage-gated cardiac sodium channel (NaV1.5). Mutations of SCN5A usually lead to impairment of NaV1.5 functionality, which is considered the main mechanism of the disease. However, SCN5A mutations are responsible for only 30% of BrS cases. Therefore, it is conceivable that other mechanisms such as post-translational modifications (PTMs) affect NaV1.5 activity. Among others, sialylation may alter ion channel activity by carrying a sugar with a negative charge. Alterations in sialylation have been described in several cardiovascular diseases, as myocardial infarction, Chagas disease, and congenital disorders of glycosylation. For these reasons, the aim was to investigate changes in sialylation in BrS patients to obtain new information on the pathogenesis of BrS. Peripheral blood mononuclear cells (PBMCs) were collected from BrS patients and healthy controls. SNA lectin, a sialic acid-binding protein, was used to characterize the protein sialylation status of PBMCs by Western blot and flow cytometry. Gene expression of enzymes involved in the sialic acid pathway was also examined. The results showed a significant decrease in intracellular and extracellular protein sialylation levels in BrS PBMCs compared with controls. In addition, changes in gene expression of enzymes involved in the sialic acid pathway were detected. Moreover, these changes correlated with clinical parameters associated with phenotypic expression of the disease, such as arrhythmogenic BrS substrate area and potential duration. These findings support that BrS should be considered a systemic disease and are consistent with the presence of overlapping non-cardiac pathologies, as epilepsy, cancer, diabetes, skeletal muscle channelopathies, and laminopathies in BrS patients. Moreover, the discovery that molecular alterations can be found in the peripheral blood of BrS patients supports the existence of a biomarker of the disease. It is a challenge to develop an effective diagnostic test to screen broadly for BrS. In this direction, a multiomic study is ongoing in our center.
Questionnaire assessments of recent exposure to environmental tobacco smoke in relation to salivary cotinine
Authors: RJ Delfino, P Ernst, MS Jaakkola, S Solomon, MR Becklake
Journal: European Respiratory Journal (1993)

The increasing evidence of the ill-health effects of environmental tobacco smoke (ETS) has prompted the search for accurate measures of exposure to ETS. The present study examined whether it was possible to enhance the ability of questionnaire-derived assessments of ETS exposure, to predict salivary cotinine. Salivary samples were obtained from 258 nonsmoking bank employees, who simultaneously answered questions detailing their exposure to second-hand smoke within the last three days. Exposure models were created, to take into account the number of smokers nearby, length of time in their presence, half-life of cotinine in bodily fluids, level of aversion to cigarette smoke and time of year. All models, including the consideration of intensity and duration of exposure combined, explained an equal amount of variance of log cotinine levels (approximately 16%). The weak relationship between questionnaire estimates of ETS exposure and cotinine, found in the present study, suggests that further investigation is needed to improve the assessment of recent ETS exposure.
Abstract P1016: Modeling Ventricular Hypoplasia In Pulmonary Atresia With Intact Ventricular Septum Using Patient-Specific Induced Pluripotent Stem Cells
Authors: Yang Yu, Shiqiao Ye, Zhaohui Xu, Karen Texter, Vidu Garg, Mingtao Zhao
Journal: Circulation Research (2022)

Pulmonary atresia with intact ventricular septum (PA-IVS) is a detrimental congenital heart disease where the pulmonary valve is not appropriately developed. Several hypotheses speculated to explain the pathogenesis of this disorder contains abnormal coronary arterial development, atypical blood flow through venous valve and atretic pulmonary valve formation. Conventional treatment strategy is pulmonary valve perforation, and PA-IVS patients after treatment present with varying degrees of ventricular hypoplasia: from single ventricle palliation (1v) to 1½-ventricle palliation (1.5v) and bi-ventricle repair (2v). Mechanistic studies are required to further explain the different levels of RV hypoplasia in PA-IVS patients. Here, we generated PA-IVS-specific induced pluripotent stem cells (iPSCs) from patients with a spectrum of RV hypoplasia. PA-IVS iPSC-derived cardiomyocytes (iPSC-CMs) contracted normally and displayed sarcomeric structures with intercalated cardiac troponin T and α-actinin. Early-stage PA-IVS iPSC-CMs exhibited a variety of compromised proliferation activities, which were not able to be rescued by Wnt signaling pathway activation. Transcriptomic profiling by bulk RNA seq suggested that pathways involved in the cell cycle and mitosis were downregulated in day13 PA-IVS-1v iPSC-CMs, but not in PA-IVS-2v iPSC-CMs. However, at later stage (day20), pathways involved in the regulation of cell division and mitosis was upregulated in PA-IVS-1v cardiomyocytes, indicating a possible developmental delay in the cardiomyocyte proliferation for PA-IVS-1v. Intriguingly, differentially expressed genes between PA-IVS-2v and control CMs were mostly enriched in the pathways relevant to glucose metabolism, mitochondrial biogenesis, and muscle contraction. The differentially involved pathways between PA-IVS-1v and PA-IVS-2v cardiomyocytes suggest that an intrinsic transcriptional program may lead to divergent degrees of cardiomyocyte proliferation and ventricular growth in PA-IVS. We conclude that patient iPSC-CMs can recapitulate cardiomyocyte proliferation defects which are involved in ventricular hypoplasia in PA-IVS.
Effects of sodium-nitroprusside and urapidil on gas exchange and ventilation-perfusion relationships in patients with congestive heart failure
Authors: S Adnot, P Radermacher, P Andrivet, JL Dubois-Rande, A Dupeyrat, F Lemaire
Journal: European Respiratory Journal (1991)

Vasodilators usually decrease arterial PO2 in patients with congestive heart failure (CHF) because of alteration in ventilation-perfusion (Va/Q) relationships. The effects of sodium nitroprusside (SNP) and urapidil (U), a new selective alpha 1-receptor antagonist, were investigated in seven patients with CHF. The distribution of ventilation and perfusion was examined using the multiple gas elimination technique. The haemodynamic responses to SNP and U were similar, cardiac index increasing by 25% with SNP and by 31% with U. Despite a similar increase of mixed venous oxygen tension, the arterial PO2 decreased from 11.3 +/- 0.8 to 9.6 +/- 0.6 kPa (p less than 0.01) with SNP but remained unchanged (11.0 +/- 0.9 vs 11.4 +/- 0.8 kPa, NS) with U. SNP and U both increased perfusion to lung units with Va/Q ratios of 0.1 or less with no change in shunt fraction. The fractional perfusion to total low Va/Q ratios (low Va/Q + shunt) was higher with SNP than with U (14.1 +/- 2.6 vs 9.5 +/- 2.3%, p less than 0.01). The results suggest that gas exchange and Va/Q relationships are altered less with U than with SNP in patients with CHF.
Abstract P2061: The Long Non-coding RNA <i>Schlafenlnc</i> As A Regulator Of Cardiac Resident Macrophage Function
Authors: Lara Althaus, Kathrin Heise, Dena Esfandyari, Seren Baygun, Evangelos Theodorakis, Julien Gagneur, Thomas Meitinger, Lars Maegdefessel, Ilka Wittig, Michael Bader, Marc Schmidt-Supprian, Anne Dueck, Stefan Engelhardt
Journal: Circulation Research (2022)

Introduction: Cardiac resident macrophages (crMΦs) constitute up to 5% of cells in the murine heart and were shown to play key roles in cardiac homeostasis and disease. Long non-coding RNAs (lncRNAs) are regulatory molecules that impact characteristics such as cell identity, proliferation or migration. However, the function of lncRNAs in crMΦ remains enigmatic. Objective: We sought to identify crMΦ-specific lncRNAs and analyze their function in vitro and in vivo to understand their role during health and cardiac disease. Methods and Results: Using RNASeq (&gt;100 million reads/sample) of purified murine crMΦs and single cell Seq of total murine myocardium in health and disease, we could identify the lncRNA Schlafenlnc as a highly enriched and abundant lncRNA in crMΦs. Employing the CRISPR-Cas system we successfully deleted the full Schlafenlnc locus in a macrophage progenitor cell line. Next, we performed RNASeq of Schlafenlnc -/- macrophages and could observe 2,660 significantly deregulated genes that were enriched in genes associated with chemotaxis and migration. In line with these findings, Schlafenlnc -/- macrophages displayed decreased chemotaxis as well as adhesion using cell-based assays. Furthermore, using RNA-pulldown experiments followed by mass spectrometry analysis and we could identify 27 interaction partners of Schlafenlnc , which are involved in processes such as mRNA processing, transcriptional regulation and alternative splicing. Finally, we are currently using cardiac functional measurements, macrophage stainings as well as single cell Seq during health and cardiac disease to analyze the function of Schlafenlnc in vivo. Conclusion: In this study, we could identify the crMΦ-specific lncRNA Schlafenlnc as a critical regulator of macrophage migratory functions. Therapeutic targeting of the evolutionary conserved lncRNA Schlafenlnc might therefore be beneficial in the treatment of inflammatory cardiac diseases.